i hope you had a backup, (you had one right ?) unless you hadn't it seems this will teach you a serious lesson about backup habits :|

just not to leave you with no response, i may suggest you take a look into your config files.. your baseurl , your db information and stuff like that.. as during the update many files may need to be re-modified after being overwritten by the update script..

*if you have a backup, you dont need to worry about anything, you can easily try recovering the update or rollback to the previous version

Word from experience here- I always find it was best to do upgrades and updates manually vs. Fantastico - I lost an install of B2Evo back in the 0.92 days for just this kind of reason and having no relevant knowledge of MySQL I lost a year of posts.

If you don't have a backup ask your host. Mosts hosts back up your files once a day. Since they offer Fantastico, they will help you in this case.